Rotary oil well drill bit



2 Sheets-Sheet l C. R. FOSTER ROTARY OIL WELL DRILL BIT Filed Jan. 25, 1938 Sept. 20, 1938.

INVENTOR Sept. 20, 1938.

c. R. FOSTER 2 Sheets-Sheet 2 Filed Jan. 25, 1938 A L I r y f INVENTOR a v I 1 I Patented Sept. 20,1938

UNITED STATES PATENT OFFICE- Olifl'ord 1:. Foster, Avoca, Tex. Application January 25, 1938, Serial No. 186,884

(Balms.

This inventionrelates to a rotary oil well drill bit andhas' for the primary object the provision of a device of this character which when brought in engagement with a formation under the weight 5 of its operating medium will assume a cutting position and will collapse when lifted from said formation so that a well drilled by the device will have a diameter greater than the collapsed diameter of the drill bit whereby the latter may be freely withdrawn from the well and will permit the use of a well casing of one diameter throughout the depth of the well, thereby materially reducing the cost of a well casing by eliminating the necessity of having to employ different size well casings throughoutv the depth of the well.

With these and other objects in view, .this invention consists in. certain novel features of construction, combination and arrangement of parts to be hereinafter more fully described and claimed. l

For a complete understandingof my invention, reference is to be had to the following [description and accompanying drawings, in which Figure 1 is a side elevation illustrating a-rotary drill bit. constructed inaccordance with my invention and showing the same in an inoperative or collapsed position. t r g d T Figure 2 is a vertical sectional view illustrating c h t .1 w: a -1- 1 F u es a v rt a ew a i w. sho

'thebit 'extendedor, in an operative position'.

Figure-4 is a sectional view taken on the line 4-4 of -Figure 1.. 1

Figure 5 isa sectional view taken onthe line 5 Hofl'lgure 1...

body of the drillbit. d p

Figure .7 is a perspective view illustrating one ofthe cutting elements, r t 40 in 'detailof the drawings, the numeral l indicates a body having wrench engaging faces 2 and one end reducedand screw threaded to forman attaching shank 3 for detachably securingthe body on a drillstem or rod. Formed 5 in opposite faces of the body I are elongated grooves 4 which also open outwardly through one end of the i The grooves 4 being formed in the body define therein aseparating partition I for'said grooves. The body I is cut awayto o expose .one end of the partition which is in the form of a head 6 having a socket I communicating with a guide bore! formed in the partition. The head 6 is disposed below the lower ends of the grooves 4. 55 Cutting elements 0 are pivotally mounted in Figure 6 is-afper's'pectiv e view illustrating a the upper ends of the grooves above the upper end of the partition 5 and each includes a shank ill, a pivotal end II and a cutting end [2. The

pivotal ends ll of the cutting elements are ar-- ranged in overlapped relation within the upper 5 ends of the grooves, the latter having communication with each other at their upper ends. The shanks l0 lie in the grooves 4 at opposite sides of the partition 5. The width of the pivotal and cutting ends of the cutting elements is greater 10 than the width of the shanks. The cutting ends l2 are beveled to present cuttingedges l3 extending the full width of the cutting ends. The

shanks Ill have formed thereon beveled stop shoulders l4 to abut beveled portions I 5 of the 15 body I when the cutting elements are in inoperative or non-cutting position. A feeder it of a conventional construction includes a head l'l slidable in the socket I and carries a guide pin I8 operable in the guide bore 8 Arms I! are piv- 20 oted on the head l1 and on the cutting elements for the purpose of. bringing about spreading of r the cutting elements by a downward movement of the body relative to the feeder due to the feeder contacting a formation and the body being 5 under the weight. of a drill'stemor the like. The cutting elements when spreadby the feeder move outwardly of the grooves 4 so as to cut a hole in a, formation of a diameter greater than the diameter of the body. 1 r l i skirt 20 ,ismounted on thebody and includes ofl'set diverging portions 2i overlying portions of the grooves4 to limitthe spreading of the cutting elements. The skirt 2. is'zsecured on the body by set bolts 22 The diverging portions 21 of the skirt terminate above the cutting ends of the cutting'elements and are 'arranged inwardly of the outer cutting corners of said cutting elements so that the latter when cutting a hole in the formation will form the hole of a diameter that the skirt 40 in entirety may move freely through. When the drill stem (not shown) is lifted, lifting the body I consequently removing weight therefrom the feeder l6 moves downwardly and the cutting elements move inwardly into the grooves 4 and in- 5 wardly of the diverging portions of the skirt. permitting the drill bit to move freely upwardly of the well without the danger of wedging against walls of the well. By forming the well of a diameter greater than the diverging portions of the skirt will permit the sinking into the well a well casing of. a diameter the same throughout the depth of-the well. I Flexible bumpers 23 are. secured on the cutting elements for the purposeof contacting the lower end of the well casing during the outward movement of the bit when being withdrawn from the well so as to assure collapsing or inward movements of the cutting. elements.

The upper portion of the skirt 20 is provided with openings 24 to expose the wrench faces 2 of g the body so that a wrench may be readily adapted thereon.

The upper portion of the body has a fluid bore 25 which opens outwardly through the shank to receive the usual cleaning fluid under pressure employed in a well. Branch passages 26 connect with the passage 25 and open outwardly in the grooves adjacent their lower ends for the purpose of directing the fluid against the cutters to re-' move cuttings therefrom.

One of the passages 26 has an auxiliary passage 21 opening outwardly at the upper end of the partition 5 so that fluid may enter the grooves adjacent their ,-upper ends to expel cuttings and foreign matter therefrom, consequently permitting the cutting elements to move freely within their grooves.

What is claimed is:

1. A rotary drill bit comprising a body having opposed grooves connecting with each other adjacent the upper end of the body, cutting elements each including a shank, a pivotal, portion and a cutting end with the pivotal portion in the connecting portions of the grooves disposing the shanks in the grooves and the cutting elements at the lowerends of the grooves and partially outwardly thereof, a pivot carried by the body and connecting the pivotal portions of the cutting elements in overlapping relation, means. carried by said body for limiting the movement of the cutting elements out of the grooves, said grooves defining therebetween a partition provided with :a recess and a guide bore, a feeder including a head slidable in said recess and a guide plunger integral therewith and slidable in the bore, con- 2. A rotary drill comprising a body having grooves communicating with each other adjacent one end of the body and separable from each other adjacent the other end of the body by a partition forming a portion of the body, cutting elements pivotally mounted in the communicating ends of the grooves and having cutting ends movable out of said grooves, a feeder slldably supported by the partition,- links connecting the feeder to the cutting elements to spread the latter to position the cutting ends outwardly of the grooves on the engagement of the feeder with a formation.

3. A rotary drill comprising a body having grooves communicating with each other adjacent one end of the body and separable from each other adjacent the other end of the body by a partition forming a portion of the body, cutting grooves communicating with each other adjacent one end of the body and separable from each other adjacent the other end of the body by a partition forming a portion of the body, cutting elements pivotally mounted in the communicating ends of the grooves and having cutting endsv movable out of said grooves, a feeder slidably suppo-rted by the partition, links connecting the feeder to the cutting elements to spread the latter to position the cutting ends ouwardly of the grooves on the engagement of the feeder with a formation, means carried by the body and including portions overlying the grooves and diverging from the body to limit the outward movement of the cutting elements with respect to said grooves, and resilient bumpers carried by'the cutting elements and projecting outwardly beyond the diverging portions of said means to engage with an obstruction for collapsing of the cutting elements into the grooves on the lifting of the body.

5. A rotary drill comprising a body having grooves communicating with each other adjacent one end of the body and separable from each other adjacent the other end of the body by a partition forming a portion of the body, cutting elements pivotally mounted. in the communicating ends of the grooves andvhaving cutting ends movable out of said grooves, a feeder slldably supported by the partition, links connecting the feeder to the cutting elements to spread the latter to position the cutting ends outwardly of the grooves portions of said means to engage with an obstruction for collapsing of the cutting elements into the grooves on the lifting of the body, said body having fluidpassages opening outwardly in the grooves for directing fluid therein and againstthe cutting elements to remove foreign matter.

CIJFFORD R. FOSTER. 

